The present invention relates to an electronic switch with a thyristor with four zones of alternating conductivity type, and, more particularly, it relates to an electronic switch having a first IGFET connected in series to the cathode terminal.
A conventional electronic switch of the relevant type is described in the journal "Solid State Electronics", volume 25, No. 5, pages 345 to 353, 1982, wherein FIG. 3 is the most relevant. This type of thyristor includes a specific field-controlled thyristor with a grounded gate electrode. For turnoff of the electronic switch, the IGFET is blocked. The current caused by charge carriers stored in the thyristor then flows through the gate electrode to ground. A disadvantage of this switch is that after turnoff of the IGFET charge carriers continue to flow from the anode-side emitter zone into the inner zones of the thyristor as long as the p-n junction between the anode-side emitter zone and the anode-side base zone is biased in the conducting direction. As a result, the quantity of charge carriers to be evacuated is increased. The clearing time is accordingly long and turnoff is delayed.
It is a primary object of the invention to provide an electronic switch of the foregoing type having a much faster turnoff than heretofore possible.